An electric vehicle powertrain typically includes one or more high-voltage alternating current (AC) electric machines, each of which is powered by a high-voltage battery pack. A power inverter module receives a direct current (DC) voltage from the battery pack and generates an AC output voltage suitable for powering the electric machines. Recharging of the battery pack may be achieved in “plug-in” electric vehicles by connecting an onboard charge coupler to an offboard AC or DC power supply, such as an available wall outlet or charging station.
When the power supply is AC, an AC-DC converter is used in a plug-in vehicle to convert an AC charging voltage into a DC voltage suitable for use by the battery pack or other DC devices. The AC-DC converter may include a passive diode bridge and actively-controlled semiconductor switches which collectively eliminate negative cycles of the AC charging voltage waveform, with the resultant voltage output thereafter filtered to provide the required DC voltage. In a DC fast-charging system, a DC power supply is used in lieu of the AC power supply, and thus the AC-DC converter is eliminated from the charging circuit in favor of a junction box.
While the plug-in charging process is controlled automatically via an onboard controller once the vehicle has been electrically connected to the offboard power supply, a typical battery charging operation requires an operator to manually connect a charging cable from the offboard power supply into the charge coupler and thereafter initiate the charging process. Other approaches for charging the battery pack include inductive charging systems and the use of charging robots. However, such alternatives may be less than optimal in terms of the required infrastructure, vehicle weight, cost, and electromagnetic compatibility and electromagnetic interference interoperability with household or other electronic devices.